Telephone switchboard system



y 3, 1949. B. c. GROH 2,468,749

TELEPHONE SWITCHBOARD SYSTEM Filed NOV. 6, 1945 INVENTOR.

BERNARD c. GROH BY MM9 ALL2;

ATTORNEY Patented May 3, 1949 TELEPHONE SWITCHBOARD SYSTEM Bernard 0. Grab, Orange, N. J assignor to the United States of America. as represented by the Secretary of War Application November ,6, 1945, Serial No. 627,082

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 2 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The invention relates to telephone switchboard systems,

Presently used switchboards are characterized by the use of ringing and listening keys. Operation of these keys is time and energy consuming, and it is a prime object of the invention to provide a simplified switchboard system that will not necessitate the use of keys. It is a further object of the invention to provide such a switchboard in a form that will be simple and rapid in operation, whereby a great number of calls may be accurately and quickly handled by a switchboard operator.

These objects, and other objects and advantages of the invention, will be apparent from the following description of a preferred embodiment of the invention read in connection with the accompanying drawing, in which the figure shows schematically the electrical circuit of a switchboard, two telephone lines and the respective terminal jacks only being shown for the purpose of illustrating the system.

Referring to the drawing, the switchboard includes a first pair of jacks It and I2 terminating a telephone line I4, a first annunciator i6 positioned across the jack H], a second pair of jacks ID and i2 terminating a telephone line M, a second annunciator l8 positioned across the jack IS, an operators set !8 and a patch cord 26.

The jack ID is a standard three conductor jack and comprises a tip contact 22, a ring contact 24 and a sleeve contact 25, the sleeve contact 26 being electrically connected to the ring contact 24 through a breaker point 23.

The jack i2 is a standard two conductor jack and comprises a tip contact 30 and a sleeve contact 32, the said sleeve contact 32 being electrically connected to the sleeve contact 25 of jack l through a conductor 34 and said tip contact being connected to the tip contact 22 of jack l0 through a conductor 35.

The annunciator I6 is a standard annunciator and includes a pivoted drop 36 responsive to a magnetic field set up by a current flowing through a coil 38. The coil 38 is connected across the jack l0, one leg of said coil being connected to the tip contact 22 through a breaker point 46.

Jacks it and I2 are identical respectively with jacks l0 and 12, each pair of jacks being the terminal equipment for a difierent telephone, line. Similarly, the annunciator I6 is identical to the annunciator l6.

For convenience of illustration, only two lines, l4 and I4, together with their respective jacks and annunciators are shown in the drawing. It will be understood, however, that this system is designed to operate with a plurality of telephone lines terminated at the switchboard.

The operators set l8 comprises a three conductor plug 42, a ringback key 44, a generator 46 and an operators phone 48. The plug 42 is a standard three conductor plug and com-prises a tip 50, a ring 52 and a sleeve 54. The ringback key 44 is a standard key and includes a breaker point 55 and a switch having breaker points 58 and 693, the points 56 and 58 normally being closed. The generator 46 is connected across the tip and the sleeve 54- of the plug 42 through the key 44 and incorporates a normally open switch 62 having breaker points 64 and 66, which switch is automatically closed by the operation of the generator in accordance with standard commercial practice. The operators phone 48 is connected across the tip 50 and the ring 52 of plug 42 through the breaker point 56 of the key 44. The sleeve 54 of plug 42 is connected to the ring 52 through the key 44 and the switch 62 in its open position. The power and filter elements of the operators set I8 are of standard commercial design and are not shown.

The patch cord 20 is of the two conductor type and is terminated by a pair of standard two conductor plugs 68 and 10.

The operation of the system will now be described, with the view of illustrating the extreme simplicity thereof. Assume that a signal is generated in the line 14 by the telephone set 12. The current .passing through the annunciator [6 will cause the pivoted drop 36 to operate, thereby notifying the switchboard operator that a signal has been impressed on the line l4. The operator will then connect the operators set [8 to the line 14 by inserting the plug 42 into the jack Ill.

The insertion of the plug 42 into the jack ID will cause the tip contact 22 of jerk I0 to move downward, thus operating breaker point 40 and thereby removing the annunciator Hi from the line, and will cause the ring contact 24 of jack it to move upward, thus operating the breaker point 28 and disconnecting the ring contact 24 from the sleeve contact 26.

It will thus be seen that the ring contact 24 of jack ill will be in electrical connection with the ring 52 of plug 42 and that the tip contact 22 of the jack 19 will be in electrical connection with the tip 59 of the said plug, thereby connecting the operators set E8 to the telephone set 12 and enabling the switchboard operator to converse with the subscriber at the telephone set 12 on line M.

Assume that the said subscriber on line M desires to be connected with the subscriber on line IA. The operator will insert the plug 68 of patch cord 20 into the jack l2 and will insert the plug 'iEl into the jack it. There will thus be established a continuous circuit between telephone set l2 and telephone set 12, the said circuit beingcompleted from the sleeve 54 of plug 52 to the ring 52 of said plug through the switch 62 in its open position and the breaker point 56 of the key H.

To ring the subscriber at the telephone set 12', the operator will then operate generator 45, thereby automatically closing switch 6?. as explained above. I It will be seen that only telephone set 12' will receive this ringing signal, inasmuch as the insertion of the plug 42 into the jack ID has caused ring contact 24 to move upwardly, thereby disconnecting the ring contact 24 from the sleeve contact 26, and isolating the line [4 from the generator 46.

There has thus been disclosed an extremely simple method of connecting two telephone lines together and of ringing one of them. The operators sole steps, after he has connected the operators set I 8 to the calling line l4, consists of joining the two lines [4, i l by means of the patch cord 28 and then turning the hand generator $6 in order to ring the called line.

In those rare cases where the operator desires to ring back the calling station, namely, telephone set 12, his sole step consists in turning the reversing key M whereby the ringing signal generated by the generator 46 will be impressed upon the line It through the breaker point 64 of the switch 62 and the breaker point 60 ofthe key 44.

After the two subscribers have been connected and have started their conversation, the operator may remove the plug 42, thereby disconnecting his set from the circuit. One or both of the annunciators [6, I6 may be left on the line a supervisory signal.

1 The foregoing description discloses what is at present a preferred embodiment of the invention, the invention being fully defined and pointed out in the appended claims:

What is claimed is:

1. A telephone switchboard system comprising means terminating a plurality of telephone lines, means whereby a signal impressed on one of said lines may be evidenced at the switchboard, an operators set adapted to be connected to said line whereby communication may be had through a switchboard operator to the said line, means whereby a second line may be connected to the first named line through said operators set, ringin means integral with said operators set whereby a signal may be impressed on said second named line, said ringing means comprising a generator connected across said second named line through a normally-open switch, said generator including means whereby the said switch will close when the generator is operated, whereby operation of said generator will impress a ringing signal on said second named line, and the said operators set further including ringback key means whereby the said generator may be placed across said first named line in order to ringback said first named line.

2. The system as described in claim 1, and means included therein whereby the ringing signal may be placed on a predetermined one of said lines.

BERNARD C. GROH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 545,921 Stromberg Sept. 10, 1895 574,255 McBerty Sept. 29, 1896 1,113,395 Winston Oct. 13, 1914 1,818,064 Johnson et a1 Aug. 11, 1931 

